T-shirt group sportswear, contrary to popular belief, is the standard and most basic product group with almost unlimited options.  In this group, Round or V-neck T-shirts, Compression T-Shirt, Fit or Oversize T-shirts and Tank-Top sportswear are manufactured.
The most common mistake is, unfortunately, the same fabric type and sewing systems are often used in the T-shirt group products mentioned above.  If you want to produce a premium sportswear, you should not use the same fabric and sewing system for the Compression T-shirt and Oversize T-shirt.